Apparatus for the electrical control of an in-line drawing machine

Abstract

An apparatus is disclosed for drawing a length of wire through a die and for supplying the wire to a using station wherein the apparatus utilizes a mechanical variable-speed drive mechanism and a sensing arm for sensing the error between the consumption and feeding rates of the wire and integrating the same. An electromechanical apparatus couples the sensing arm to the variable-speed drive so that the full range of drive ratios of the variable-speed mechanical drive mechanism can be utilized without the occurrence of a pull-back force at the wire. The mechanical pivoting of the sensing arm is translated to an electrical signal by way of the electromechanical apparatus which incorporates a plunger for oscillatory motion in response to the pivoting of the compensator arm. An electrical device is sensitive to the displacement of the plunger in a manner to provide a signal having a linear relationship to the magnitude of the displacement by the plunger caused by its oscillatory movement. The electrical device is not in direct physical contact with the plunger, thereby providing a friction free transition of mechanical movement of the plunger to an electrical signal.

We claim: 
     
       1. An apparatus for drawing a length of wire through a die and for supplying the wire to a using station, said apparatus comprising: a support,   a drum rotatably mounted on said support, said drum having an entrance end portion for receiving the wire from the die and having an exit end portion from which the wire is supplied to the using station, there being a coil of wire wrapped around said drum between entrance and exit end portions and said coil being composed of a number of wraps in a single layer,   a variable speed drive mechanism for rotating said drum thereby drawing wire onto said entrance end portion and to supply wire off of said exit end portion,   said drive mechanism comprising:   a motor,   an input pulley connected to be rotated by said motor,   an output pulley connected to rotate said drum, and   an endless belt connected between said pulleys to transmit rotation from said input pulley to said output pulley,   at least one of said pulleys being adjustable in effective diameter and operable when adjusted to change the speed of said output pulley and said drum,   a sensing arm mounted for oscillation about a pivot on said support and engaging the wire being supplied from the exit end portion of said drum to said using station in such a manner as to form such wire into a loop, said arm increasing the size of said loop when pivoted in one direction and permitting the size of said loop to decrease when pivoted in the opposite direction,   means for biasing said arm in said one direction, and   electromechanical means for changing the effective diameter of said at least one pulley and thereby changing the speed of said drum response to pivoting of said arm and without a pull-back force occurring at said arm as a result of said change in diameter.   
     
     
       2. An apparatus as set forth in claim 1 where said electromechanical means includes a slidable shaft mounted in a housing for axial movement in first and second directions in response to clockwise and counterclockwise pivoting, respectively, of said arm for changing the electrical characteristics of a device incorporated into a control circuit operatively coupled to a motor for changing the effective diameter of said at least one pulley. 
     
     
       3. An apparatus as set forth in claim 1 wherein said electromechanical means includes first means for converting the mechanical pivoting of said arm to an electrical signal and second means for returning said electrical signal to a mechanical movement whereby said mechanical movement changes the effective diameter of said at least one pulley. 
     
     
       4. An apparatus as set forth in claim 3 wherein said electromechanical means includes a low-pass filter for removing frequency components of said electrical signal greater than a predetermined value. 
     
     
       5. An apparatus as set forth in claim 2 wherein said electromechanical means produces an electrical signal whose amplitude corresponds to the relative displacement of said arm as it oscillates about its pivot and whose frequency corresponds to the frequency of the oscillations. 
     
     
       6. An apparatus as set forth in claim 5 wherein said electromechanical means includes a filter for effectively removing the relatively high frequency components comprising said electrical signal. 
     
     
       7. An apparatus as set forth in claim 1 wherein said electromechanical means includes first means for representing the rotational speed of said drum as a first value of a predetermined unit of measurement, second means for representing the relative pivotal position of said arm as a second value of a predetermined unit of measurement and third means for determining the difference between said first and second value and adjusting the speed of said drum if said difference is greater than a predetermined amount. 
     
     
       8. An apparatus as set forth in claim 7 wherein said electromechanical means includes a low-pass filter for filtering said second value before said second value is applied to said third means. 
     
     
       9. An apparatus for drawing a length of wire through a die and for supplying the wire to a using station, said apparatus comprising: a support,   a drum rotatably mounted on said support, said drum having an entrance end portion for receiving the wire from the die and having an exit end portion from which the wire is supplied to the using station, there being a coil of wire wrapped around said drum between entrance and exit end portions and said coil being composed of a number of wraps in a single layer,   a variable-speed drive mechanisms for rotating said drum thereby drawing wire into said entrance end portion and to supply wire off of said exit end portion,   said variable-speed drive mechanism being responsive to the pivoting of a sensing arm pivoted on said support and engaging the wire being supplied from the exit end portion of said drum to said using station in a manner to cause pivoting of said arm when said using station consumes said wire at a speed different from the speed said wire is supplied by said exit portion of said drum,   said variable-speed drive mechanism including an electromechanical device for converting the mechanical pivoting of said arm into an electrical signal for use by a control circuit to adjust the speed of said drum in a manner to approximate a supply of said wire at a rate equal to the consumption of said wire by said using station,   said electromechanical device comprising, (a) a plunger member mounted for oscillatory movement along its longitudinal axis in response to the oscillatory motion of said sensing arm;   (b) a substantially sealed chamber for receiving a first end of said plunger member and a second end of said plunger member extending from said sealed chamber through a bearing surface to make mechanical contact with said sensing arm;   (c) a sensor mounted within said sealed chamber whose electrical characteristics are sensitive to a change in the position of said second end of said plunger member within said sealed chamber; and   (d) means for limiting the extent of said oscillatory movement of said plunger member such that any change in the position of said second end of said plunger member is linearly related to the change in the electrical characteristics affected by the positional change of said second end.     
     
     
       10. An apparatus as set forth in claim 9 wherein the variable-speed drive mechanism includes; a motor,   an input pulley connected to be rotated by the motor,   an output pulley connected to rotate the drum and,   an endless belt connected between the input and output pulleys to transmit rotation from the input pulley to the output pulley,   at least one of the pulleys being adjustable in effective diameter and operable when adjusted to change the speed of the output pulley and the drum, and   a second motor forming part of the control circuit responsive to the electrical signal from the electromechanical device for changing the effective diameter of the at least one pulley and thereby changing the speed of the drum in response to pivoting of the arm, without a pull-back force occurring at the arm as a result of the change in diameter.